This invention relates to battery powered gas sampling pump devices small enough to collect environmental air samples on individual workers.
Traditional personal air sampling techniques utilize air flow rates of about 2,000 cc/minute. However, flows may be necessary as low as 5 cc/minute and for sample bag filling, may go up to 4,000 cc/minute. It is therefore desirable to provide variable flow rates from 5 cc/minute to 4,000 cc/minute with a controlled flow system. It is also desirable to provide for accurate volume samples of 3% or lower by controlling the pump flow. It is further desirable to have a self-calibrating flow system incorporated in the pump system which can compare pump flow rate against a primary flow calibrator such as that shown in U.S. Pat. No. 4,860,590.
It is also desirable to accurately monitor pump run time. It is believed that the ability to time air flow blockage or sudden removal of an air filter has not heretofore been available so as to provide accurate run time data. In addition, it is desirable to provide a system which maintains all air sampling information in the event of a battery failure.